This field has standardized surprisingly fast. Nowdays, all operating systems provide the same set of basic services (processes, threads, paging, files, etc) derived from Unix evolution. More advanced operating systems (with true objects instead of raw files) seem to all have been cancelled (including Cairo).
In concept, the only remaining difference between various operating systems is where the operating system stops and where the applications start. The two extreme according to this criteria being Linux (minimal operating system), and Windows (maximal operating system). (See the usage of these words below before constesting this.)- more details -

This was a very straight forward choice: since the advantages of the rich environment provided by maximal operating systems is rather thin compared to the lack consistency over time and security, not talking about freedom, and basic operating system features are now common to all decent(*)
operating systems. Pliant relies only on these basic features.